Watanabe Kenji, Praseuth Alex P, Wang Clay C C
Department of Pharmacology and Pharmaceutical Sciences, University of Southern California 1985 Zonal Ave PSC 718 Los Angeles, California 90033, USA.
Curr Opin Chem Biol. 2007 Jun;11(3):279-86. doi: 10.1016/j.cbpa.2006.11.041. Epub 2007 May 7.
Customizing biosynthesis of natural products to yield biologically active derivatives has captivated scientists in the field of biosynthetic research. To substantiate this goal, there are scores of obstacles to consider. To create novel metabolites by mutating amino acid residues in wild-type enzymes, a researcher must broaden the range of the enzymes substrate tolerance and increase its turnover rate during reaction catalysis. In the past decade, numerous gene clusters responsible for the biosynthesis of notable natural products have been identified from a variety of organisms. Several genes coding for type III polyketide synthases, particularly the chalcone synthase superfamily enzymes, were recently uncovered and expressed in E. coli. Furthermore, it was observed and reported how these recombinant enzymes are capable of producing essential metabolites in vitro. Three of the type III polyketide synthases, chalcone synthase, octaketide synthase and pentaketide chromone synthase, have been characterized and their active sites subjected to rational engineering for biosynthetic production of their analogs. Because they are encoded in a single open reading frame and are post-translationally small in size, type III polyketide synthases are ideal targets for protein engineering. The relative ease with which these genes are expressed makes molecular biological manipulation to obtain mutated enzymes more procurable, ameliorating analysis of its biosynthetic pathway. In summary, time devoted to modification of biosynthetic proteins and unravelling of the detailed reaction mechanisms involved in biosynthesis will be shortened, paving the way for a much wider scope for metabolic engineers in future. This review focuses on the use of chalcone synthase, octaketide synthase and pentaketide chromone synthase for rational biosynthetic engineering to generate molecular diversity and pursue innovative, biologically potent compounds.
定制天然产物的生物合成以产生具有生物活性的衍生物，这吸引了生物合成研究领域的科学家。为了实现这一目标，有许多障碍需要考虑。要通过突变野生型酶中的氨基酸残基来创造新的代谢产物，研究人员必须拓宽酶的底物耐受性范围，并提高其在反应催化过程中的周转率。在过去十年中，已经从多种生物体中鉴定出许多负责合成著名天然产物的基因簇。最近发现了几个编码III型聚酮合酶的基因，特别是查尔酮合酶超家族酶，并在大肠杆菌中进行了表达。此外，还观察并报道了这些重组酶如何能够在体外产生必需的代谢产物。已经对三种III型聚酮合酶，即查尔酮合酶、八酮合酶和五酮色酮合酶进行了表征，并对其活性位点进行了合理设计，以生物合成其类似物。由于它们编码在一个单一的开放阅读框中，并且翻译后尺寸较小，III型聚酮合酶是蛋白质工程的理想靶点。这些基因相对容易表达，使得通过分子生物学操作获得突变酶更加可行，从而改善了对其生物合成途径的分析。总之，用于修饰生物合成蛋白和阐明生物合成中涉及的详细反应机制的时间将缩短，为未来代谢工程师提供更广阔的空间。本综述重点介绍了利用查尔酮合酶、八酮合酶和五酮色酮合酶进行合理的生物合成工程，以产生分子多样性并追求创新的、具有生物活性的化合物。
